The present invention relates to an aerodynamic profile with an adjustable flap, having a forward profile area as well as a rearward profile area situated in a downward current, bounded by pressure-side and suction-side covering skins, the pressure-side covering skin and the suction-side covering skin converging, in the rearward profile area, at a trailing profile edge.
Such aerodynamic or lifting-force-generating profiles are typically lifting surfaces and rotor blades on the trailing edges of which landing or control flaps are arranged. As a result of an up and down movement of such a flap, an aerodynamic control effect is caused in a known manner. This is required particularly because of the different aerodynamic requirements during take-off and landing so that it has to be possible to implement corresponding flap positions in the course of different flight phases.
A conventional airplane wing structure with a flap is described, for example, in German Patent Document DE 41 07 556. In this structure, a landing flap is arranged on the trailing edge of the airplane wing. The landing flap is rotatably linked to a carriage movably arranged on a guide rail and is thereby displaceable, while a linked lever changes the angle of the landing flap in an extending movement. In the take-off or landing phase, the wing surface is enlarged by moving the flap out toward the rear, and the profile contour is changed by the angle change.
However, with a view to future applications, it is problematic that, with previously known control flaps, expected rising demands on passenger planes, as a result of an increase in air traffic, will not be met or will not be met sufficiently effectively. One of these demands is, for example, the need to increase the climbing and descent rates for reducing noise in approach zones and for increasing take-off and landing frequency. In addition, in the future, improvements to adaptability are required for an optimal Ca/Cw ratio for reducing consumption because, as a result of the high traffic volume, adaptation by way of the traveling altitude is possible only to a limited extent. Furthermore, load redistributions increasingly have to be taken into account for reducing weight and consumption.
In order to meet these new demands, most recently, novel small control flaps, called miniflaps, have been examined. Such miniflaps differ from conventional flaps with depths of 10-30% clean wing chord depth in that they only have very low depths of from 1-3% and, as in the case of a split flap, have a stationary part and an extended part. One miniflap of this type is the so-called Gurney flap which is known in the field of aerodynamics and is described, for example, in “Computational Evaluation of an Airfoil with a Gurney Flap”, C. S. Jang, J. C. Ross, R. M. Cummings, ALAA-92-2708-CP. The Gurney flap is arranged at the end of an aerodynamic profile as a rigid thickening fixedly on its pressure-side covering skin. In this case, the flap encloses a fixed angle with the pressure-side covering skin, which typically amounts to maximally 90°. A turbulence system is formed in the wake of the flap, which improves the top surface flow and causes a strong flow deflection at the trailing edge of the profile which, in turn, clearly improves the lift of the aerodynamic profile. An airtight construction of the transition area between the pressure-side covering skin and the flap can improve the lift-increasing effect of the miniflap. So far, it has only been possible to technically ensure the required gap tightness at the transition area by rigidly connecting the flap with the profile underside. The known Gurney flap therefore has the disadvantage that its aerodynamic effect cannot be varied.
It is therefore an object of the invention to further develop an aerodynamic profile based on the known operating principle such that the flap mounted on the profile has an adjustable construction and its aerodynamic effect can be adjusted. It is another object of the invention to construct the aerodynamic profile with the adjustable flap in a maintenance-friendly manner, with a simple construction, and at reasonable production cost.
These objects are achieved by way of an aerodynamic profile in which, in the rearward profile area on the underside of the pressure-side covering skin, a flap is swivellably disposed such that, in an inoperative position, the flap, pointing in the flow direction, rests against the contour of the pressure-side covering skin and, in a deflected condition, encloses an angle with the pressure-side covering skin. An airtight hinge connection is integrated in the flap so that a turbulence system improving the flow conditions is formed on the side of the flap sheltered from the wind.
This arrangement has an advantage in that an airtight flap linkage is ensured during adjustment of the flap so that the aerodynamic effect of the flap can be adjusted. As a result, adaptability to the rising demands on today's passenger planes mentioned above is ensured.
An arching-in is preferably formed in the pressure-side covering skin in the transition area to the flap. This arching-in is adapted to the shapes of the hinge connection and the flap. In this case, the arching-in radius corresponds to the curvature of the hinge connection. As a result, the aerodynamic drag of the flap is reduced in the inoperative condition and, because it rests against the hinge connection, the arching-in has an advantageous effect on the gap tightness of the transition area.
Particularly preferably, the flap is of a fiber composite material. As a result, integration of the hinge connection in the flap is permitted in a simple manner. In addition, such a flap has sufficient stability that it can extend over a wide area in the wing span direction. Simultaneously, a weight reduction is achieved, which is advantageous particularly with respect to fuel consumption. Another advantage is that the height of the flap or of the hinge connection is very low because of the narrow material thickness of the fiber composite. As a result, hardly any additional aerodynamic drag is generated in the inoperative condition.
According to a first embodiment of the invention, the flap is of a laminated, folded prepreg material; in this case, an airtight loop area is formed along the fold, and a sliding material is inserted and a torsion bar can be introduced into the loop area. Because of the folded arrangement, an airtight flap linkage is reliably ensured along the entire flap dimension in the wing span direction. In addition, the flexibility of the material easily permits close contact with the arching-in provided in the pressure-side covering skin. This additionally improves the airtightness of the flap linkage.
According to another embodiment, the flap is formed of unidirectionally and multidirectionally reinforced fiber composite arrangements which are sewn to one another, impregnated and hardened. Consequently, in the area of the unidirectional fiber composite arrangement, a reinforced airtight loop area is created into which a sliding material is inserted, and a torsion bar can be introduced for the rotatable bearing of the flap. Likewise, in the first embodiment, the flap, constructed of a sewn-together fiber composite arrangement, is advantageously characterized in that an effective airtight flap linkage is permitted with a corresponding dimensional adaptability to the pressure-side covering skin. In addition, this further development, in comparison to the arrangement of a prepreg material, has the advantage that the loop area is reinforced by the unidirectional fiber composite arrangement, preferably in the thickness direction. In addition to the reinforcement, among other things, a delamination of the flap in the symmetry plane starting from the loop area is prevented.
The loop area expediently has milled-out areas so that the flap has a plurality of individual loops into which the torsion bar can be introduced. In a simple manner, this creates space for mounting a corresponding counterpart of the hinge connection on the torsion bar without impairing the gap tightness of the flap linkage.
Preferably, a corresponding counterpart is also arranged on the torsion bar. The counterpart can be of a fiber composite, aluminum, or another sheet-metal-type metallic material, and can have fastening loops. The torsion bar is non-rotatably connected with the fastening loops and is rotatably disposed in the loops of the flap, or vice versa. The possibility of being able to use different materials is advantageous here.
Furthermore, recesses are advantageously provided in the pressure-side covering skin. These recesses significantly facilitate fastening of the flap on the pressure-side covering skin. In this case, it is expedient to introduce corresponding fastening areas of the fastening elements into the recesses and to mount them by gluing and/or riveting on the pressure-side covering skin.
Advantageously, connection elements are arranged between the suction-side and the pressure-side covering skin. These connection elements are constructed in a rib shape and are arranged extending in the flow direction. As a result, a monolithic construction is achieved, which is advantageous with respect to reducing weight.
A connection profile is expediently arranged between the spaced covering skins. By way of the connection profile, the rearward profile area can be mounted on the forward profile area. In this manner, the rearward profile area can be easily exchanged in the event of damage to the flap or to another component. This can be implemented, for example, by the opening up of a bolt connection between the connection profile and rearward profile areas. In this case, care should be taken to adapt the dimensions of the forward and rearward profile areas correspondingly in order to obtain a constant flow surface.
In addition, it is advantageous to provide a fastening part on the underside of the flap, to which fastening part the adjusting lever is linked by way of a hinge point.
The actuator is advantageously arranged in the forward profile area. As a result, an exchange of the rearward profile area can be carried out unhindered, so that short maintenance times are required.
It is expedient to produce the suction-side covering skin, the pressure-side covering skin, the connection elements, and the connection profile of aluminum. This ensures sufficient protection against lightening.